. College collection of palaeontology. 158 PORIFERATA. No. 501. Receptaculites Oweni, Hall. This sponge was hollow, of a discoidal, cyliudrical or globular shape, and with a small protuberance near the center of the lower side which is thought to indicate the point where growth began. The body-wall has a complex structure. It consists of three layers. The inner and outer integments are composed of numerous rhomboidal calcareous plates, so peculiarly arranged as to give fragments the appearance of an engine-turned watch-case. Numerous small, straight, hollow spicula connect the inner and outer
. College collection of palaeontology. 158 PORIFERATA. No. 501. Receptaculites Oweni, Hall. This sponge was hollow, of a discoidal, cyliudrical or globular shape, and with a small protuberance near the center of the lower side which is thought to indicate the point where growth began. The body-wall has a complex structure. It consists of three layers. The inner and outer integments are composed of numerous rhomboidal calcareous plates, so peculiarly arranged as to give fragments the appearance of an engine-turned watch-case. Numerous small, straight, hollow spicula connect the inner and outer layers. The animal has some points of resemblance to the Foramiuifera. It ranges through the Silurian. Trenton group, Rockford, 111. No. 503. [1174, Cast]. Siphonia (Hallirhoa) costata, Lamoureux. Polypothecia septemloba, Benett. The fossil Sponges belonging to this genus, have a comparatively symmetrical form. The body is bulbous and supported by a slender stem, which is composed of very fine parallel longitud- inal tubes, terminating on the surfaces of the central cavity. The base of the stem was fixed by root-like processes. Tlie genus does not occur above the Chalk. From the Upper Greensand, Westminster, England. No. 503. [1177, Cast]. Siphonia pyriformis, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ward's Natural Science Establishment, inc. Rochester
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